Styrene-butadiene copolymer, properties

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

Butadiene copolymers are mainly prepared to yield mbbers (see Styrene-butadiene rubber). Many commercially significant latex paints are based on styrene—butadiene copolymers (see Coatings Paint). In latex paint the weight ratio S B is usually 60 40 with high conversion. Most of the block copolymers prepared by anionic catalysts, eg, butyUithium, are also elastomers. However, some of these block copolymers are thermoplastic mbbers, which behave like cross-linked mbbers at room temperature but show regular thermoplastic flow at elevated temperatures (45,46). Diblock (styrene—butadiene (SB)) and triblock (styrene—butadiene—styrene (SBS)) copolymers are commercially available. Typically, they are blended with PS to achieve a desirable property, eg, improved clarity/flexibiHty (see Polymerblends) (46). These block copolymers represent a class of new and interesting polymeric materials (47,48). Of particular interest are their morphologies (49—52), solution properties (53,54), and mechanical behavior (55,56). 

Between the 1920s when the initial commercial development of mbbery elastomers based on 1,3-dienes began (5—7), and 1955 when transition metal catalysts were fkst used to prepare synthetic polyisoprene, researchers in the U.S. and Europe developed emulsion polybutadiene and styrene—butadiene copolymers as substitutes for natural mbber. However, the tire properties of these polymers were inferior to natural mbber compounds. In seeking to improve the synthetic material properties, research was conducted in many laboratories worldwide, especially in the U.S. under the Rubber Reserve Program. 

Prior to 1940, the use of synthetic elastomers in linings was negligible, but the advent of the Second World War, and the consequent loss of natural rubber sources to the Allies, led to the use of synthetic rubber, namely a styrene-butadiene copolymer which, whilst not having all the properties of natural rubber, proved to have adequate anti-corrosive performance. 

This block copolymer has substantially different physical properties as compared to a random styrene-butadiene copolymer. 

Solution (S-SBR) consists of styrene butadiene copolymers prepared in solution. A wide range of styrene-butadiene ratios and molecular structures is possible. Copolymers with no chemically detectable blocks of polystyrene constitute a distinct class of solution SBRs and are most like slyrcnc-buladicne copolymers made by emulsion processes. Solution SBRs with terminal blocks of polystyrene (S-B-S) have the properties of self-cured elastomers. They are processed like thermoplastics and do not require vulcanization. Lithium alkyls are used as the catalyst. 

A specific example is used to illustrate the MLR methods, as well as the other quantitative calibration methods discussed in this section. In this example, a total of 70 different styrene-butadiene copolymers were analyzed by NIR transmission spectroscopy.39 For each of these samples, four different properties of interest were measured the concentrations of czs-butadiene units, trans-butadiene units, 1,2-butadiene units, and styrene units in the polymer. The NIR spectra of these samples are overlayed in Figure 8.12. These spectra contain 141 X-variables each, which cover the wavelength range of 1570-1850 nm. 

Preparation, Properties and Applications of. High Styrene Content Styrene-Butadiene Copolymers... 

Selected blends of styrene-acrylonitrile copolymer (30 to 55%), a styrene-butadiene copolymer grafted with styrene and acrylonitrile (45 to 70%), and a coal-tar pitch (0 to 25%), were prepared. Physical properties of the experimental blends were determined and statistical techniques were used to develop empirical equations relating these properties to blend composition. Scheff canonical polynominal models and response surfaces provided a thorough understanding of the mixture system. These models were used to determine the amount of coal-tar pitch that could be incorporated into ABS compounds that would still meet ASTM requirements for various pipe-material designations. ... 

These properties determine how carbon black will be distributed within the blend. These properties are not those of the filler but are the essential properties of the matrix. The matrix thus has strong influence on particle distribution. SEM studies showed that high vinyl polybutadiene and styrene-butadiene copolymers had morphologically identical carbon black distribution. However, their mechanical properties were very different. NMR analysis indicated that the difference in mechanical behavior is related to the interaction and more precisely to the molecular motions in rubbery matrix. 

Mn 2 to 4). In olefin polymerization as well as CO copolymerization, a Umited conversion of liquid 1-olefin (co)monomers is yet to be overcome in many cases. As an example of properties that could find potential appUcation, polyolefins contain a negligible proportion of double bonds by comparison to styrene-butadiene copolymers, a hydrocarbon polymer currently prepared by free-radical emulsion polymerization on a large scale. This can result in a considerably higher stability towards UV-Ught and air of polymer films formed from polyolefin latexes. 

For electrostatic and steric stabilization, the particles can be viewed effectively as colloids consisting of a soft and deformable corona surrounding a rigid core. Colloidal particles with bulk elastomeric properties are also available. These particles, which are generally of submicron size, are developed and used as reinforcement additives to improve the Impact resistance of various polymer matrices [28-30]. The rubber of choice is often a styrene/butadiene copolymer. The presence of chemical groups at the matrix-filler interface leads to improved adhesion between them. Typically, the addition of about 30% by volume of these elastomeric particles increases the impact strength of a brittle glassy polymer like polystyrene by up to a factor of 10. For some applications, particles with more complex architecture have been... 

K. Stephens and C. L. Beatty, "Effect of Ozone Exposure on the Physical Properties of Butadiene and Styrene/Butadiene Copolymers", contained in this publication. 

Figure 5-3. Temperature dependencies of G, G" and tan 8 for styrene butadiene copolymer. [After L. E. Nielsen, Mechanical Properties of Polymers, Reinhold, New York, 1962.]...

Hartsock DL, Stacy NE. Preparation, properties and applications of high styrene content styrene-butadiene copolymers. In Scheirs J, Priddy DB, editors. Modern Styrenic Polymers Polystyrenes and Styrenic Copolymers. New York Wiley ... 

Styrene butadiene copolymers come in a wide variety of types, with a similar wide variety of properties. As discussed in Section 4.6, HIPS (High Impact PS), is partially a graft copolymer and partially a physical blend of polystyrene and polybutadiene. HIPS, which is opaque, typically contains 2 to 15 weight % polybutadiene. In addition to significantly decreased brittleness, it has a broad processing window and is easy to thermoform, either as sheet or as extruded foam. 

The properties of bitumen paints (Section 2.14.2) can be favorably modified and adjusted to suit practical requirements by combination with other film-forming substances. For example, the thermoplasticity can be reduced and/or mechanical properties (e.g., hardness, extensibility) can be improved by adding polymers such as polyethylene, polypropylene, polyisobutene, and styrene-butadiene copolymers. The chemical resistance can also be improved high-quality corrosion protection coatings can be obtained by combination with alkyd resins. 

Rubber consumption is dominated by tyre production. In these, conveyor belts, and pressure hoses, thin layers of either steel wire or polymeric fibre reinforcement take the main mechanical loads. These layers, with rubber interlayers, allow flexibility in bending, whereas the reinforcement limits the in-plane stretching of the product. The applications are dominated by natural rubber and styrene butadiene copolymer rubber (SBR). Other rubbers have specialised properties butyl rubbers have low air permeability, nitrile rubbers have good oil resistance, while silicone rubbers have high and low temperature resistance. Rubbers play a relatively small role in this book, but the rubbery behaviour of the amorphous phase in semi-crystalline thermoplastics is important. 

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